1. Field of the Invention
The present invention relates to air conditioner control means for controlling the refrigerating ability in the refrigeration cycle of an air conditioning device in a vehicle that has a travel use motor. More particularly, the invention relates to air conditioner control means for limiting the refrigerating ability in the refrigeration cycle to maintain, above a predetermined level, the air-cooling ability of a radiator for air-cooling the cooling water that cools electric parts, related to a travel use motor, such as a travel use motor inverter mounted on the vehicle.
2. Description of the Related Art
In a refrigeration cycle of a vehicle having a travel use motor, such as a hybrid car having a travel use engine as well as a travel use motor, it is a general practice to arrange a first heat exchanger (condenser) that removes, by being air-cooled, the heat which the coolant has absorbed from the air introduced into the vehicle compartment, and a radiator (hereinafter referred to as EV radiator) that air-cools the cooling water to cool various electric parts mounted on the hybrid car in series with a radiator (hereinafter referred to as the engine radiator) that air-cools the cooling water for cooling the travel use engine, in the direction in which the cooling air flows. There has further been proposed a refrigeration cycle for controlling the rotational speed of an air-cooling fan depending upon the temperature of the electric parts to maintain the cooling water temperature below a predetermined value to prevent a decrease in ability, caused by an increase in the temperature, of the electric parts.
From the standpoint of saving space in modern hybrid cars, it has been attempted to fabricate the EV radiator and the engine radiator integrally together as an integrated radiator, and to arrange the first heat exchanger and the integrated radiator in series in the direction in which the cooling air flows, instead of arranging the three units, i.e., the first heat exchanger, the EV radiator and the engine radiator in series in the direction in which the cooling air flows.
Here, the temperature of the cooling water (hereinafter referred to as engine cooling water) for cooling the engine is permitted to rise up to 110° C., and can be sufficiently cooled even with the air that has received heat from the coolant through the first heat exchanger. However, the temperature of the cooling water (hereinafter referred to as EV cooling water) for cooling the electric parts is permitted to rise up to only 65° C. to protect the electric parts. It is, therefore, probable that the cooling water cannot be air-cooled down to 65° C. by the air that has received heat radiated from the coolant through the first heat exchanger.